The great biblical waterway is now little more than a shallow, unimposing trickle of sludge, a murky body of water that is in danger of withering into nothingness.

"Is that it? Seriously, that's the Jordan? I could jump it," declared one mightily unimpressed American teenager, as we crossed the river from the Kingdom of Jordan to the Palestinian West Bank one blindingly bright afternoon back in October.

There's no real mystery as to how the river famous as the reputed site of Jesus' baptism has sunk so low.

"Everybody's been taking water from the Upper Jordan because everybody needs it," said Clive Lipchin, director of the Center for Transboundary Water Management at Israel's Arava Institute, and one of a number of water experts alarmed by the decline of a river that was never particularly substantial in the first place.

What remains of the Jordan springs from its source high in the Lebanese mountains, before it passes near the Syrian border and along the Jordanian, Israeli, and Palestinian frontiers.

It's one of the most complicated and conflict-ridden regions on Earth, and that goes some way toward explaining the Jordan River's current predicament.

Fighting Over Water

Cooperation between Israel and its Arab neighbors is rare, which leaves the river and its problems hostage to 65 years of distrustful and often hostile coexistence.

"There's no water because Israel steals it all," said Mohammed, a Bedouin goat herder who tends his brother's flock in the parched Jordanian hills near Mount Nebo, where Moses is said to be buried.

"Jordan and the Palestinians are responsible because they waste everything," Yitzhak Adami, a Jerusalem taxi driver, told me, as we wove our way toward a hilltop Jewish settlement in the occupied West Bank.

But as fraught as relations between Israel and Jordan remain, despite the peace treaty they signed in 1994, it's Syria's struggles that preoccupy water policymakers' thoughts.

Indeed, the river might be described as the latest victim in a brutal Syrian civil war that is thought to have killed at least 130,000 people and displaced almost seven million so far. (Read "Damascus: Will the Walls Fall?" in National Geographic magazine.)

Almost 2.5 million refugees have fled Syria to date (up from 550,000 in January last year), and 600,000 of them have settled in arid and water-impoverished Jordan, a country of slightly fewer than 6.5 million citizens. (Read "Journey Without End" in National Geographic magazine.)

Environmental issues have understandably been a very distant second to humanitarian concerns, but the ongoing chaos and fast-increasing mass of refugees needing water have stretched the Jordan River's already desperately meager flow to a trickle.

Refugees Straining Capacity

Some communities in the dusty, pancake-flat expanse of northern Jordan will tell you their cities' water resources long ago reached a desperate state. The new pressures could bring them to the breaking point.

An old farmer sleepily perched next to his fruit stand outside Mafraq sadly shook his head and just repeated "too many people, too many people," when asked about the influx of new arrivals.

At less than 10 miles (16 kilometers) from the Syrian frontier, and 20 miles (32 kilometers) from Deraa, where the opening salvo of the Syrian revolution was fired in March 2011, Mafraq was always going to be the first port of call for many refugees.

But no one could have guessed the enormity of the Syrian exodus.

Syrians now far outnumber longtime residents, and non-Syrian Arabic accents are a comparative rarity in the teeming coffeehouses around Mafraq's potholed main drags.

Over 80 percent of Syrians who are registered with the UN's refugee agency in Jordan arrived in 2013, and a third of them are in Mafraq Governorate.

Many of the established inhabitants of Jordan are originally refugees themselves.

Several waves of Palestinians arrived after the creation of Israel in 1948, and thousands of Iraqis settled there after the Gulf War in the early '90s and during the civil war that rocked their country a few years after the American invasion in 2003.

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Israelis relax by the Sea of Galilee, which is fed by the Jordan River; seven years of drought have drastically lowered the lake's level.

PHOTOGRAPH BY PAOLO PELLEGRIN, NATIONAL GEOGRAPHIC

Water Disputes Boiling Over

But as the Syrian population mushrooms, the local residents' sympathy for their beleaguered neighbors has waned, and it's water that's at the root of their dissatisfaction.

Water efficiency in Mafraq is down by more than 50 percent since 2011, meaning more water is being wasted, and water quality has diminished significantly as a consequence of excessive water extraction to accommodate a provincial population that has more than doubled.

Some residents are particularly wary of the consequences of inadequate sewage treatment in areas overcrowded with refugees. They fear wastewater will eventually seep into the ground and poison the water table.

"The risk of contamination is minimal," according to Thomas Palo, the UN's in-house water expert in Jordan, but it's just one of many rumors to have taken root in the increasingly toxic atmosphere.

One Jordanian civil servant told me that Syrian government sympathizers had been caught trying to poison local water supplies, but a UN refugee worker asked about the reports answered, "That's just part of the rumor mill," noting that he'd also heard allegations of spies starting fires with laser pointers.

Zarqa, Jordan's second largest city, lies just to the north of the capital, Amman, and is home to a sizeable refugee community. A water dispute erupted into a neighborhood brawl there last summer, after a Jordanian of Palestinian extraction accused a Syrian of tapping into his water supply.

Refugee Camps Guzzling Water

Most of the refugee population lives in underdeveloped pockets of Jordan's cities, but 6 miles (10 kilometers) east of Mafraq, 150,000 or so Syrians have made their home in Za'atari, the second largest refugee camp in the world and now the fourth largest settlement in Jordan. (Related: "First Person: Five Things I Learned in Syrian Refugee Camps.")

It frequently appears on the news as a devastating illustration of the human toll of the Syrian conflict, but it's also a compelling reminder of the additional strain levied on the region's water resources.

Four million liters (more than one million gallons) of water a day is brought into the camp by 255 tankers, which works out to about 40 liters (10.5 gallons) per person; an emergency daily standard is 18-20 liters.

It's an excessive amount, UN officials admit, but camp occupants have made a habit of taking matters into their own hands, and additional supply is needed to ensure there's enough to iron out the imbalances.

"There's been a lot of privatization of water resources," Palo said, putting a euphemistic spin on the semi-criminal activity that has included some strong community leaders assuming ownership of public wells.

Some 71 percent of Za'atari residents have installed their own toilets, 8 percent have their own water tanks, and many families have hooked up personal hosepipes.

There are even 1,500 private washing machines, all of which tap into the camp water supply.

And it's not just water that's reappropriated: Many washrooms and other communal sanitation facilities, which are needed to reduce the risk of disease, are often dismantled soon after they're built, with their parts plundered for private use.

"People do pretty much what they want," said Kilian Kleinschmidt, the German UN official who administers Za'atari. "They've connected themselves to electricity and water, whether we would have done it that way or not," he said.

Syrians are frequently accused by local Jordanians of having a cavalier attitude to water use, and it's not an entirely groundless charge. Many refugees come from parts of Syria where there's an abundance of water, and most haven't yet accustomed themselves to Jordan's more straitened environmental circumstances.

"They're not water conscious," said Kleinschmidt, who's trying to phase in a system of water meters, which he hopes will assuage the complaints of locals resentful of the Syrians' access to free water.

A Dry Oasis

The ever-increasing number of displaced Syrians has forced farms and factories to look elsewhere for water.

"Because the refugees take from the aquifers, that water has to be compensated for by the water from the river," said Munqeth Meyhar of Friends of the Earth Middle East (FOEME) when we met at his office in an unassuming industrial district of Amman.

Some Jordanians will have you believe Syrians are to blame for their severe water shortage, Meyhar said.

"The water situation was okay before all this," said Maher Elias, who works in a clothes shop in Amman.

But long before the Syrian war exploded, Jordan had greatly overstretched its water resources.

The oasis at Azraq, in the desert to the east of the capital, dried out in 1990, with the water table dropping from 4 meters above the surface to 20 meters below it today. Groundwater is now being pumped into the oasis, once known as a bird-watching hot spot, to keep it alive as a tourist attraction.

Both of Jordan's principal aquifers have been overpumped by 300 percent, which means a fall of about a meter a year—far quicker than they can be replenished.

Such excessive extraction is also having a grave effect on water quality.

The water from the first borehole in the recently built refugee camp at Azraq was unusable, and engineers are now digging a second, deeper well a few miles outside the camp—though Azraq will open only if 600 refugees a day arrive in Jordan, instead of the current 300.

Population Spiking

A newly tapped aquifer near the Saudi border should help lighten the load on the river and the northern aquifers, but there's no contending with the region's breakneck population growth.

Amman's towering skyscrapers, glitzy new suburbs, and slumlike neighborhoods on the outskirts tell the tale of a population that grew by 86 percent between 1990 and 2008, according to the World Bank.

A UN study suggests Jordan's population will peak at 11.5 million by 2050, but that doesn't include refugees, "and the experience of Jordan is that refugees never leave," said Munqeth Mehyar.

It's a similar story across the river, where Israel's population increased by 56 percent and that of the Palestinian territories grew by 106 percent within a similar timeframe.

Such sizeable spikes in population have, of course, necessitated significant increases in food production.

About 65 percent of the water Jordan takes from the river goes toward agriculture. And with UN agencies spending four million dollars a month providing food for Za'atari alone—three million of which goes to the local economy—it's becoming ever more profitable to cultivate previously unused patches of land.

Israel Saves Water

Israel allots an even greater share of its river water to agriculture.

The early Zionists made it their mission to "make the desert bloom," and they did, but at a tremendous water cost to the river and the Sea of Galilee—also known as Lake Tiberias and one of several spots that are claimed to be Jesus' baptism site.

Israel's national water system diverts water from the Jordan's flow as it passes through the Sea of Galilee in the north of Israel, and redistributes it to the country's densely populated core and arid, largely previously uninhabitable south.

Historically it's drawn heavily on groundwater, but seven years of drought have drastically lowered the lake's level and forced the country to reduce its consumption of the Jordan River's water.

From a high of 400 million cubic meters (mcm) eight years ago, FOEME estimates that Israel withdrew around 160 mcm from the Sea of Galilee last year. Jordan, by comparison, pumps an average of 300 mcm a year from the Yarmouk River, the Jordan River's largest tributary.

Israel recently announced plans to release 30 mcm back into the Jordan, which is seen as a positive first step, but not enough to aid the river's rehabilitation. "It's a miniscule amount that will do nothing for the river," according to the Arava Institute's Lipchin.

This does, however, mark a potential upturn in the Jordan's fortunes.

The rapid development of high-tech desalinization plants along Israel's Mediterranean coast has greatly diminished the country's dependence on freshwater sources. Half of Israel's drinking water is now desalinated, a figure the government hopes to increase to around 70 percent, or 700 mcm, by 2020.

Water from the Sea of Galilee is still about a third of the cost of desalinized water, which requires a lot of electricity to produce and so is prohibitively expensive in the north of Israel far from the plants. But even there, treated wastewater has largely replaced freshwater for crop irrigation.

"Israel's water economy is very healthy," said FOEME's Mehyar in Amman, noting that Israel recycles 87 percent of its water, with Spain the next best in the world at 21 percent, and Jordan coming in at under 10 percent. (Learn how to reduce your own water footprint.)

Environmental concerns are certainly responsible in part for Israel's swift advances in desalinization, but it has long coveted an independent water supply shielded from regional upheaval.

Tensions with Syria and Jordan over their plan to divert water away from Israel contributed in part to the 1967 war, which Israel won and thereafter annexed the Golan Heights, which abut the Sea of Galilee, and began its occupation of the West Bank.

The Syria Connection

Of course, Syria also should be involved in any effort to rehabilitate the Jordan.

Successive Syrian governments have severely restricted the Jordan's flow by building a series of dams along the Yarmouk River, which runs mostly through its territory.

But "even before the war, [FOEME] couldn't contact any kind of civil society group, because they didn't have any civil society groups," Mehyar said.

A Syrian contacted in Jordan, who declined to give his name for fear of imperiling family members still in Damascus, confirmed this account, saying, "there was never any activism in Syria. That kind of thing just wasn't possible in a restricted political situation."

Now in a cruelly ironic twist, Syria's near-constant power outages over the past few years have bolstered the Yarmouk River and reduced the usual trail of pollutants drifting downstream.

Without electricity or gas to power their machinery, many Syrian farmers haven't been able to plant and seed their fields, and with no crops to irrigate, water consumption has declined significantly.

"The unrest has almost been positive for the river," Mehyar said with a grimace.

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The waste from fish ponds like this one goes into the lower Jordan River, contributing to its pollution.

PHOTOGRAPH BY PAOLO PELLEGRIN, NATIONAL GEOGRAPHIC

Palestinian Complications

Very little water is drawn from the Lower Jordan, which is pitifully small by the time Syria, Israel, and Jordan have dirtied and drained it of 96 percent of its water. But even if it were to be of use, it's uncertain that the West Bank, which flanks the river on its southwest side, would have any access to it.

The Jordan Valley is largely closed to Palestinians and is restricted to Israeli military use and Jewish settlements, whose crops benefit from a wastewater pipeline from East Jerusalem.

The roughly 2.1 million Palestinians in the West Bank get most of their water from an aquifer deep underground, but they are nevertheless party to many of the Jordan's problems. Much of their waste flows down toward the river, past the settlement date palm plantations, and pollutes the river.

"Raw sewage discharged from Palestinian communities flows freely in many streams," said Haim Gvirtzman, a professor of hydrology at the Hebrew University of Jerusalem.

"In contrast to the extensive improvement of water supply installations, mainly due to Israel's assistance, no significant progress has been made by Palestinian wastewater treatment plants," he added.

The situation is more complicated than that, though.

The Palestinian Authority doesn't have complete jurisdiction over much of the West Bank, and must receive authorization from Israel to build sewage treatment plants in all areas outside of the major Palestinian cities. And that permission isn't always forthcoming: It took 12 years to build a facility near Nablus in the north of the West Bank.

Environmentalists see water divisions as emblematic of a wider inability to crack the Israeli-Palestinian conflict.

"The whole water and environment issue, which is today completely solvable at a low political cost for Israel and high political gain to Palestine, is being held hostage to the failure of not moving forward in the other final status peace process issues," said Gidon Bromberg, FOEME's Tel Aviv director.

Can "Red to Dead" Work?

If it seems as if Friends of the Earth Middle East appears in every Jordan River and Dead Sea–related discussion, that's because it's pretty much the only environmental group willing or able to reach across the Israeli-Arab divide.

"Everyone [in Jordan] tries to avoid dealing with Israel," Mehyar said, but he and his colleagues in Tel Aviv and Ramallah—the seat of the Palestinian Authority—feel that without cross-border cooperation, it's futile to try to salvage a river that ranges across multiple countries.

A recently agreed deal to revive the Dead Sea by channeling Red Sea water into the fast-shrinking saline lake neatly captured the complications of cooperation.

The plan, known as "Red to Dead," is basically a front for a water exchange, which will see Jordan give arid southern Israel desalinized water from its soon-to-be-built plant on the Red Sea coast, and Israel in return pass a similar amount to Jordan's refugee-laden north.

The exchange is very much in both countries' interest, and even though the Jordanian government, and most water experts, know the "Red to Dead" plan isn't practical, "they keep talking about it because they don't want to go to the Jordanian public to say we have a swap deal with Israel," Mehyar said.

And while politicians on both sides of the river dither and debate, the Dead Sea really is dying, and it's the most eye-catching illustration of the Jordan's decline.

Robbed of its sole inflowing water source, the famously salty waters of the lake at the lowest point on Earth are evaporating fast in the unrelenting heat.

A number of spa hotels that were once positioned on the water's edge now employ tractor-drawn trailers to haul tourists up to half a mile to the shoreline along hastily tarmacked tracks that are extended every year. In the waters' stead, scattered debris lies alongside signs warning of sinkholes created by freshwater eating away at the salt.

"It's not affecting tourism yet, but if it carries on like this it will be a big problem," said RM Esther, who works at the Ein Gedi Spa on the Israeli shore.

Some Positive Signs

Elsewhere, however, there are signs that Israelis and Jordanians are beginning to work together to the river's advantage.

Jordan appears to be overcoming its aversion to public dealings with Israel by buying some of its desalinized water, while the current Israeli Minister of the Environment, Amir Peretz, has shown himself much more amenable to cross-border cooperation with the Palestinian Authority than his hawkish predecessor was.

A proposed Jordan River Peace Park is a source of particular hope to its FOEME backers. They envision an island national park where Jordanians, Israelis, and Palestinians, who so seldom meet, might congregate and try to overcome their differences.

It's idealistic in the extreme, but the signing of the "Red to Dead" deal has heartened environmentalists who work in a region unaccustomed to agreements of any sort."We're still years away from a potential deal, but this lays groundwork and is certainly very positive," said Lipchin of the Arava Institute.